Problem: Solve for $x$ : $7\sqrt{x} + 9 = 3\sqrt{x} + 5$
Explanation: Subtract $3\sqrt{x}$ from both sides: $(7\sqrt{x} + 9) - 3\sqrt{x} = (3\sqrt{x} + 5) - 3\sqrt{x}$ $4\sqrt{x} + 9 = 5$ Subtract $9$ from both sides: $(4\sqrt{x} + 9) - 9 = 5 - 9$ $4\sqrt{x} = -4$ Divide both sides by $4$ $\frac{4\sqrt{x}}{4} = \frac{-4}{4}$ Simplify. $\sqrt{x} = -1$ The principal root of a number cannot be negative. So, there is no solution.